The present invention relates to a synchronizer circuit and is directed to, for example, a synchronizer circuit which converts an asynchronous signal from the rotary drum or the like of an electronic deck calculator with a printer into a synchronous signal.
In an electronic desk calculator, etc., information processing, such as calculations, is carried out using regular synchronous signals (clock pulses). That is, signals shifting through various logic parts of the calculator are mostly synchronized with the clock pulses. Where a printer is used as the means to indicate set numbers, a calculated result, etc., information must be transmitted from the body of the calculator to the printer in conformity with the movement of the printer. In other words, the information must be transmitted in synchronism with the movement of the printer.
The general printer has a rotary drum in which a plurality of numerals and letters are carved, and the printer side accordingly requires that the movement of the drum (what numeral or letter has moved under an electromagnetic hammer) be connected into an electric signal and that the electric signal be sent to the calculator body.
The electric signal thus sent from the printer must be converted into a signal synchronized with the clock pulse, in order that it may be subjected to logical operations, such as an AND operation and an OR operation, with the aforesaid signals being processed through the various logic parts of the calculator body. The synchronism herein stated is different in meaning from the foregoing synchronism between the calculator and the drum, and in this respect, care for avoiding the confusion of both will be necessary.
The signal sent from the printer is generally inferior with respect to the rise and fall (sharpness) of the waveform, and the period during which it transmits between two levels is very long.
Accordingly, when this signal is fed into the logical circuit of the calculator without any change, the logical circuit remains in the transition region of its input-output transmission characteristic for a long period, and the state in which the output level is determined neither as a logical 1 nor as a logical 0 continues for a long period of time.
Since, in this manner, the signal generated in the printer does not have good rising and falling (sharpness) characteristics, it has been unreasonable to convert it into the synchronous signal immediately.
The present invention has been made in order to solve the problem stated above, and provides a circuit which converts an asynchronous signal having inferior rising and falling characteristics into a synchronous signal having good rising and falling characteristics.
In uses such as the electronic desk calculator, more importance is attached to power consumption and the degree of integration than to speed, and as means for fulfilling this purpose, there is the insulated gate field-effect transistor semiconductor integrated circuit, and such integrated circuit is chiefly used at present.
It is, accordingly, another object of the present invention to provide a synchronizer and converter circuit which is constructed of insulated gate field-effect transistors.